Process for producing sized ferroalloy particles

ABSTRACT

A PROCESS FOR DISINTERGRATING A STREAM OF MOLTEN FERROALLOY INTO SOLIDIFIED SPHEROIDAL TO SPHERICAL CONFIGURATIONS FOR USE AS ADDITIVES IN METAL PRODUCING FURNACE OPERATIONS OR THE LIKE.

May 2, 1972 YOUNG ETAL 3,660,544

PROCESS FOR PRODUCING SIZED FERROALLOY PARTICLES Filed April 15, 1970 2 Sheets-Sheet l MOLTEN METAL INVENTORS C. FRANK YOUNG gzlARLEs M. OFFENHAUER a it 3M;

ATTORNEY May 2, 1972 c. YQUNG ETAL 3,660,544

PROCESS FOR PRODUCING SIZED FERROALLOY PARTICLES Filed April 15, 1970 2 Sheets-Sheet 2 MOLTEN METAL INVENTORS C. FRANK YOUNG CHARLES M. FFENHAUER ii zgm ATTORNEY United settes Patent 01 ice 3,660,544 Patented May 2, 1972 Int. Cl. B01j 2/14 US. Cl. 2648 7 Claims ABSTRACT OF THE DISCLOSURE A process for disintegrating a stream of molten ferroalloy into solidified spheroidal to spherical configurations for use as additives in metal producing furnace operations or the like.

FIELD OF THE INVENTION This invention relates to a process for producing substantially uniform ferroalloy sizes having a somewhat spheroidal configuration. The process consists in subjecting a molten metal to a centrifugal force sufiicient to direct and disperse the molten metal into a radially defined zone wherein the dispersed metal particles contact and roll upon the surface within the zone so that the roll contact action, when added to the surface tension action of the metal, will be sufficient to draw each particle into a somewhat spheroidal to spherical shape. The motlen to semi-molten ferroalloy particles are then discharged from the radial zone and quickly solidified into their adopted shapes. The ferroalloy particles or shots, so produced are relatively uniform in size, however, the size can vary depending upon the degree of centrifugal force imparted to the molten metal and the contour of the radially defined zone.

DESCRIPTION OF THE PRIOR ART Various methods are employed to produce small finless ferroalloy sizes for use as additives in metal alloy furnace operations. A uniformly sized ferroalloy charge is required to be relatively free of fines and fins so that when the charge reaches its final destination, it can be fed into a metal producing furnace without fear that fines will explode or otherwise hamper the operational mode of the furnace.

One method for producing small sized ferroalloy charges is to cast them to the size desired. This method is expensive and still yields end alloys having fins which require another operation to remove. In addition, sizes between 8 Tyler mesh up to inch, and preferably A inch, are difiicult to cast on a large scale basis.

'Another method presently used is in casting alloy sizes in large chills and then crushing the alloy by conventional means to produce various alloy sizes. Due to the friability of the alloy, a considerable amount of fines and off-size particles are produced which decrease the net output quantity of a selected alloy size. Separating the selected size from the off-size elements requires another operation which adds additional time and expense to the overall production operation.

The disadvantage of present methods in producing an alloy size within a somewhat narrow range is in the large amount of off-size pieces that are co-produced. The present invention provides a method wherein the off-size pieces are greatly minimized and the selected alloy sizes are somewhat spheroidal to spherical in configuration. In addition no expensive crushing, casting or forming operation is required.

SUMMARY OF THE INVENTION Broadly, the process of this invention comprises subjecting a stream of molten liquid within an insulated zone to a centrifugal force snfiicient to direct and disperse the molten stream into a radially defined sinuous type passage wherein the molten to semi-molten particles of the dispersed stream contact and roll upon at least one curvilinear surface of the passage. The molten liquid can be any material that solidifies at room temperature such as molten metal. The rolling contact action, together with the surface tension action of the molten to semimolten liquid, is sufiicient to influence the small particles into adopting a somewhat spheroidal to spherical configuration. Preferably, the molten to semi-molten particles should roll upon a rotating member having an inclined curvilinear surf-ace and then be tangentially projected to the opposite surface of the passage having a declining curvilinear surface so that maximum circumferential contact between the spheroidally forming particles and the surfaces of the sinuous type passage can be obtained. To increase this contact action, the opposite surfaces of the passage may be counter-rotated with respect to each other thus subjecting the spheroidal to spherical particles to an increased spirally rotating motion, such motion derived from combining the radial motion due to the centrifugal force and the circular motion due to the counter-rotating surfaces. It is this combination of radially directed contact force and circular imparted contact force, in addition to the relatively low surface tension force, that shapes the dispersed particles into spheriodal to spherical configurations.

The molten to semi-molten alloy partciles, while still subject to the combined forces, are ejected from the peripheral ,outlet of the sinuous type passage and quickly quenched or solidified in their adopted spheroidal to spherical shapes. A receptacle or the like containing a quenching medium may be employed to catch and solidify the alloy shapes, such shapes being somewhat spheroidal to spherical in degree depending on the centrifugal force, the degree of the shape of the curvilinear surfaces, the number of peaks of the sinuous passage and the particular viscosity of the molten liquid used. A sinuous passage having at least one peak is required to insure that the dispersed particles will roll on at least one incline curvilinear surface thus providing sulficient contact force which can be added to the surface tension force to appropriately shape the particles. The inlet of the sinuous passage can be made adjustable so as to regulate at least the maximum size of the dispersed particles being forced through the passage.

DEORIPTION OF THE DRAWING The invention will be more readily understood by reference to the drawing wherein:

FIG. 1 is an elevated sectional view taken through the center of the apparatus of this invention.

FIG. 2 is an isometric view of the rotating anvil of the apparatus showing the spiral path taken by the dispersed particles.

In FIG. 1 hot molten metal is axially fed upon rotating circular anvil 1 which is made from a material that can withstand the high temperature of the molten metal, such material being graphite, aluminum, magnesia, cast iron or any refractory metal that will not react with the molten metal. The anvil has a conically shaped projection 2, centrally disposed and extending upward. An inclined curvilinear surface 3 extends radially outward from projection 2 and before reaching the peripheral vicinity, the surface assumes a zero slope and then slopes slightly downward. A rotatable drum 4 has an axial opening 5 into which the molten metal is directed to contact projection 2. The undersurface' 12 of drum 4 is curved with a mating curvilinear surface to that of surface 3 but extends radially outward further so that when axially disposed on top of anvil 1 a sinuous type passage 13 is defined. It is also possible to have anvil I extend further out than the drum so as to terminate the sinuous passage in an upward direction. The drum, like the anvil, can be made from any material that can withstand a high temperature environment without reacting with the molten metal being disintegrated into small particle sizes.

Motor 6 is used to rotate anvil 1 while motor 7 rotates drum 4 in a counter direction. Cone-shaped skirt 8 is used to protect the anvils rotating means from any misdirected metal particles.

Receptacle 9 may be a simple annular type receptacle or at least two arcuate receptacles which when juxtaposed will form an overall annular receptacle. This receptacle, containing a quenching or solidifying medium 14, is placed below and radially outward from peripheral outlet 15 of the sinuous passage so as to be in a position to catch the exiting spheroids 11.

Cylindrical shell 10, in addition to supporting drum 4, provides a protection barrier from misdirected alloy particles exiting from the sinuous passage.

In the operational mode, molten metal, such as ferroalloy, is fed into aperture in drum 4 and directed to contact projection 2. The rate of the metal feed is variable but must be slow enough to allow sufficient contact with rotating projection 2 so that the metal can be centrifugally projected and dispersed into the sinuous type passage 13 between drum 4 and anvil 1. With the anvil rotating, the dispersed metal particles are forced to roll and slide upon curvilinear surface 3 whereon each particle travels in a spiral path as exemplarily shown in FIG. 2-. Each particle traveling in this spiral path is subjected to a radially applied centrifugal force A and a circular or rotating force B which is normal to force A and together the forces subject the particle to maximum circumferential contact with surface 3 of revolving anvil 1. The molten spheroidally forming particles are then tangentially projected onto the curvilinear undersurface 12 of the drum where they continue to roll thus increasing the rolling contact acting thereon. A greater roll contact between the spheroidally formed particles and the drum can be obtained by rotating drum 4 in a counter direction to that of anvil 1.

The somewhat spheroidal to spherical particles 11 are then ejected at peripheral outlet 15 in a downward direction into a receiving receptacle 9'. A quenching medium of any non-reactive gas or liquid, such as water, oil, liquid salt, liquid glass and liquid silicon would quickly solidify the particles into their adopted shapes. A jet of cold air disposed in the vicinity between the passage outlet and the receptacle may also be used to elfect solidification of the particles. A screen-like net or mesh liner within the receptacle may be employed for facilitating the removal of the particles. It is also possible to employ a revolving type mesh liner which could be used to direct the particles to a preselected section in the receptacle where a conveyor, inclined radially outward through a suitable opening in the lower portion of the cylindrical shell, would continuously remove the particles and direct them into a collection container.

Since conical projection 2 continuously contacts the molten metal feed thereby being subject to wear, it may be made replaceable by providing a threaded or geometrically shaped lower portion which can be threaded or ininserted into a mating recess in the center of the anvil.

The degree of the curvilinear passage, as to slope and the number of peaks, is variable and deepnds on the degree of sphere required for the solidified alloy. The peripheral outlet of the passage may terminate with a positive slope thereby directing the exiting alloy particles in an upward direction.

Cir

Molten ferroalloys suitable for use with this apparatus include ferrosilicon, ferromanganese, ferrochrome, ferrochrome silicon, magnesium ferrosilicon, silicomanganese and the like.

EXAMPLE Using an apparatus similar to that shown in the drawing, several heats of molten 50% ferrosilicon, each weighing about 30 pounds, was pound into the central opening of a graphite drum to contact a rotating conical protrusion of a graphite anvil. The conical protrusion broke the stream of ferrosilicon into small particles and discharged them into a sinuous passage similar to that shown in the drawing. The ferrosilicon particles were made to spirally roll and slide upon the revolving anvil and then were tangentially projected to contact and roll upon the under curvilinear surface of the drum. The particles under the force of surface tension and roll contact action were infiuenced into adopting a somewhat spheroidal to spherical shape by the time they reached the peripheral outlet of the passage. They were then discharged from the sinuous passage and caught in a plurality of circular receptacles positioned below and concentrically outward from the passage outlet. The receptacles were filled with water which immediately quenched the caught ferrosilicon particles into their adopted shapes, such shapes being somewhat spheroidal to spherical in configuration.

The solidified particles were then subjected to a screen analysis test and found to contain 92% by weight sized between 8 Tyler mesh and inch.

The term somewhat spheroidal is intended to mean the shape of discrete particles, such as shots or pellets, which may have protrusions disfiguring a true spheroidal shape. These protrusions occur from the solidification of the particles prior to the particles assuming a true spheroidal to spherical shape. Although the particles depart from a true spheroidal to spherical shape, they are still commercially usable as long as they fall within a particular size range.

It is to be understood that a higher percentage of uniformly shaped particles can be obtained by rotating the drum of the apparatus of this invention in a counter direction to that of its mating rotating anvil and/or by extending the radial length of the sinuous passage so formed by the drum and anvil since either or both of these modifications will increase the spiral path upon which the particles will roll thereby subjecting the particles to a greater circumferential contact with the surfaces of the passage. This increased circumferential contact, due to the increased radial and circular rolling motion imparted to the particles, will aid in influencing the particles to adopt a more spheroidal shaped configuration.

What is claimed is:

1. A process for disintegrating a molten stream of material solidifiable at room temperature into somewhat spheroidal to spherical shaped particles, comprising:

(a) directing a molten stream of material onto an insulated rotating member,

(b) subjecting said material thereon to centrifugal force suflicient to radially project and disperse said material into particles through a radially defined sinuous type passage having at least one peak therein wherein said particles therein contact and roll upon at least one inclined curvilinear surface defining said sinuous type passage to shape said particles into a somewhat spheroidal to spherical configuration under the combined action of surface tension and roll contact upon said curvilinear surface, and

(c) collecting said shaped particles in a circumferentially confined receptacle which is concentric with said sinuous type passage and which contains a quenching medium to solidify the molten particles to their adopted somewhat spheroidal to spherical configuration.

2. The process of claim 1 wherein said molten stream is a liquid metal stream.

3. The process of claim 1 wherein the shaped particles are discharged from the sinuous-type passage in a downward direction.

4. The process of claim 1 wherein increased rolling contact is obtained by having the sinuous type passage comprised of two circular counter-rotating members, each with mating curvilinear surfaces spaced apart so as to form at least a one peak sinuous passage.

5. The process of claim 2 wherein said molten liquid metal is selected from the group consisting of ferro-silicon, ferro-manganese, ferrochrome, ferrochrome silicon, magnesium-ferrosilieon, or silicomanganese.

6. The process of claim 1 wherein said quenching medium is selected from the group consisting of water, oil, air, liquid salt, liquid silicon, and liquid glass.

References Cited UNITED STATES PATENTS 2,739,348 3/1956 Rayburn l82.5 RR 1,210,097 12/1916 Perry et a1 182.5 RR 2,294,588 9/1942 Pazsiczyl 182.5 RR 2,994,102 8/1961 Payton 2648 ROBERT F. WHITE, Primary Examiner J. R. HALL, Assistant Examiner US. Cl. X.R. l82.5 RR

UNITED STATES PATENT owner; CERTIFICATE OF CORRECTION Patent No. 3 5 Issue Date May 2 1972 Inventor) C. F. Young & C. M. Offenhauer It is certified that error appears in the above-identified potent and that said Letters Patent are hereby corrected as shown below:

In the Specification:

Column 2, line 33, "partciles" should be particles Column 3, line 68, after "or" delete "in'-' Column 3, line 71, "deepnds" should be depends Column 4, line 9, "pound" should be poured Signed and sealed this 15th day or May 1973.

(SEAL) Attest: n ng M.FLET( 2HER JR ROBERT G O I'TSCHALK es lng OfflCGI" v Commissioner of Patents 

